1. Field of the Invention
This invention relates to hot plates, and more particularly, to a hot plate system that incorporates a natural or synthetic stone hot plate, and to a design where the heat source can be a flame source. The invention relates to stored heat device such as a stone that is positioned beneath a vessel such as a drinking cup, and heat is transferred from the stored heat device to the vessel to maintain the liquid in the vessel at an elevated temperature.
2. Brief Description of the Prior Art
Stored heat cooking vessels have been used for many years. They have been found to be particularly beneficial where a heating element such as a stone can be heated in a stove or on the campfire and the stored heat energy used to maintain foods at an elevated temperature or to slowly cook the food. U.S. Pat. No. 2,640,478, A. F. Flournoy, illustrates such a device. This consists of an outer container which has a heat storing element in its interior base and supports above it a cooking vessel having an enclosing lid. The vessel appears much like a double-boiler cooking pan with the heat element in the position of the water. U.S. Pat. No. 2,419,416 illustrates a holder and warmer for liquid containers using the same principles involved in the cooking vessel.
U.S. Pat. No. 4,258,695, entitled, Stored heat cooking utensil, discloses a stored heat cooking utensil which consists of an outer container, a cooking vessel, a heat storage element, a lid for enclosing the outer container and cooking vessel, a handle for manipulating the cooking vessel and the heat storage element, and a container handle which serves as a carrying handle for the cooking utensil and a lid securing device. The heat storage element is a disk of soapstone having a metal band around its exterior perimeter having its side perpendicular to the stone's top and bottom.
U.S. Pat. No. 4,806,738 discloses an electric plate, that is composed of soapstone. Soapstone is a greyish alteration product of species of rock containing very little silicon acid, including talcum and magnesite or dolomite. It can be readily machined, as well as enduring acids and alkalis and also heat to some extent.
The term "natural stone" is used in this specification and the appended claims to mean stone that occurs in the natural environment, as distinguished from synthetic or artificial stone-like materials manufactured by man, or other man-made imitation materials that are merely intended to have the appearance of stone. Examples of natural stone are natural granite, limestone, marble, serpentine stone, amphibole stone (such as homblende), and soapstone.